1. Field of the Invention
The present invention relates to a table creation method, table creation apparatus, storage medium, and program.
2. Description of the Related Art
As a conventional technique, a table creation method for creating a color separation table into coloring material colors has already been proposed by the present applicant which includes: a method of creating a gray line color separation table 1 into black from white; a method of creating a plurality of color separation tables 2 into primary and secondary colors from white; a method of creating a plurality of color separation tables 3 into black from the primary and secondary colors; and a method of performing an interpolation process to obtain table data among the color separation tables 1, 2, 3 based on the tables (Japanese Patent Application No. 2000-214386).
The interpolation process method comprises: dividing a color space constituted of a cube into six tetrahedron areas; and subjecting each area to the interpolation process.
However, the above-described conventional example comprising: dividing the color space constituted of the cube into six tetrahedron areas; and subjecting each area to the interpolation process has a disadvantage that a pseudo contour is generated in an area boundary. Moreover, depending on the method of creating the color separation tables 1, 2, 3, distortion occurs in a partial area during an internal interpolation process, and a disadvantage occurs that the pseudo contour of a reproduced image is generated.
To solve the problem, an n×n filtering process is used with respect to a two-dimensional plane, and a smoothing process for inhibiting the pseudo contour from being generated by an n×n×n filtering process is used with respect to a three-dimensional space. However, simply by the n×n or n×n×n filtering process, values of a gray line (color separation table 1) which must not be changed, or a line defining a maximum chroma (color separation tables 2, 3) are changed, and there is a problem that the filtering process cannot simply be applied.
Furthermore, in the smoothing by the simple filtering process, there is a problem of deterioration of granularity caused by: 1) deviation of a gray component or dark ink replacement starting point; and 2) impaired smoothness in the gray component or dark ink replacement start.